<!DOCTYPE html>
<html>
<head>
	<title>11 margin</title>
<style>
	#cont {
		width: 1000px;
		height: 500px;
		border: 1px solid red;
	}

	#test1 {
		width: 400px;
		height: 200px;
		border: 1px solid blue;
		/*margin: 10px上 20px右 30px下 40px左;*/
		/*margin: 10px上 50px右	没有分配，取对边;*/
		/*margin: 10px;*/
		float: left;
	}
	
	#test2 {
		width: 400px;
		height: 200px;
		border: 1px solid blue;
		float: left;
	}
	
	#test3 {
		width: 800px;
		height: 200px;
		border: 1px solid blue;
		float: left;
	}
</style>
</head>
<body>
	<div id="cont">
		<div id="test1"></div>
		<div id="test2"></div>
		<div id="test3"></div>
	</div>
</body>
</html>